1. Field of the Invention
This invention relates to an image stabilized optical system having a reticle, and more particularly to an optical system with a reticle provided with an image stabilizing means in which an image is stabilized with respect to the reticle.
2. Description of the Prior Art
There have been known various optical systems having a reticle disposed on the focal plane of an objective like a sighting telescope. By utilizing a scale on the reticle, the size of an object can be known when the distance to the object is known and vice versa.
There have also been known various optical systems with an image stabilizing means.
When a telescope or binoculars are supported by hands, the vibration of the hands is liable to transmit to the telescope or binoculars which results in vibration of the image viewed therethrough. Particularly when the optical instrument such as the telescope or the binoculars is carried and used in a vehicle like an aircraft or motorcar, the image is vibrated and the quality of the image viewed is lowered. This is because the optical axis of the optical instrument is vibrated and the angle of the emanating optical axis is fluctuated. The vibration transmitted to the optical system is amplified by the optical system to the degree in proportion to the magnification of the optical system.
In order to avoid the vibration of the image viewed through the optical instrument or focused in an optical instrument, there have been proposed various kinds of image stabilized optical instruments. Some of these instruments are disclosed in U.S. Pat. Nos. 3,473,861, 3,608,995, and 3,608,997, Japanese Patent Publication No. 52(1977)-23262 (U.S. patent application Ser. No. 300,528), and Japanese patent application No. 52(1977)-88145 (U.S. patent application Ser. No. 926,382).
These image stabilized optical instruments are mainly directed to stabilization of an image viewed therethrough. Therefore, when it is provided with a reticle disposed on the focal plane of the objective, the image formed on the reticle vibrates relative thereto when the optical instrument is vibrated. Accordingly, it becomes difficult to measure the size of the image by the scale, even if the image itself is stabilized.